Monday
Aug082011
by 
Bishop Hill
Bishop Hill Shrinking trees
Aug 8, 2011 Climate: MWP Anthony Watts has a must-read story about the discovery of yet another confounding factor in the science of dendroclimatology.
Aug 8, 2011 Climate: MWP
Reader Comments (44)
Reminds me of the 'global warming stunts sheep' story.
http://www.independent.co.uk/news/science/how-global-warming-shrank-st-kildas-sheep-1729609.html
Tree growth is characterised by coordination in which cell divison results in increasing girth, and cell elongation which results in increasing height.
It has always been assumed that tree ring data, increasing girth, was proportional to temperature, so I suppose it would have been also assumed that tree height was also proportional to temperature, a coordinated effect. This research on tree height suggests the opposite.
So if tree ring data, increasing girth, is not actually proportional to temperature then dendroclimatology is in deep dog pooh.
Maybe one day they will find a use for all this research, in the meantime, what weather produces the best firewood, would be interesting for us rural folk, suffering from fuel poverty
golf charley
You'll be pleased to know that rising CO2 is probably quite good for making more firewood by enhancing photosynthesis :-)
The article deals with a continent wide phenomenon, not a local one. There is nothing that says within a small area the same thing occurs.
The largest might become smaller, but the happiest of the smaller may and probably still are the taller of the smaller.
Richard Betts, more CO2 would seem to be a good thing then? ;-)
golf charley
I don't deny that more CO2 has its upsides as well as its disadvantages! And ironically, stabilising atmospheric CO2 concentrations would take away the benefits of CO2 effects on photosynthesis quicker than it would take away the impacts of climate change, as the climate would be expected to continue to warm for a while after stabilising CO2.
golf charley:
When I planted my arboretum down here in Devon, I was told by the locals that it was an ideal climate for growing trees. Lots of rainfall and not too cold (tho after the last three hard winters when I lost a few saplings, I'm not sure about that).
Richard Betts:
I've yet to see any evidence that CO2 affects the climate. I note that you say "expected to continue to warm". Not much scientific certainty there.
There's 1200 cricket bat willows planted near me, all planted from cuttings on the same day 8yrs ago, the smallest diameter at the base is about 8", the largest is about 18", a back of the envelope calculation says the tree ring density of this crop is not a good proxy for anything!
Philip
My escallonia hedge (also in Devon) failed to make it through the last 2 winters, so earlier this year I replaced it with beech - and have since spent the whole time trying to defend the new plants against drought!
IPCC AR4 WG1 has plenty of evidence that CO2 affects climate.... :-)
"IPCC AR4 WG1 has plenty of evidence that CO2 affects climate..."
Actually, assessment reports contain no evidence unless they come attached with sandwich baggies that have stuff (evidence) in them. Otherwise they are what is called second-hand information. ;)
Andrew
Frosty, if the 1200 willows near you were planted only 8 years ago, then of course they don't conform to the tree ring / temperature rule.
That rule only allies to paleo-trees, and Briffa clearly demonstrated that trees grown since 1960 are just anarcho-trees that refuse to conform to proper paleo-tree rules.
Richard Betts, perhaps you could help me locate where in AR4 WG1 is the evidence that CO2 affects climate. Maybe I missed it. The relevant chapter seems to be Ch 2 (and I see you were an author). All I can find is on page 140 :
"The simple formulae for RF of the LLGHG quoted in Ramaswamy et al. (2001) are still valid. These formulae are based on global RF calculations where clouds, stratospheric adjustment and solar absorption are included, and give an RF of +3.7 W m–2 for a doubling in the CO2 mixing ratio."
Ramaswamy et al. is of course not a scientific paper but the previous IPCC report! I don't think that the IPCC quoting numbers from its previous report counts as very convincing evidence as far as Phillip and I are concerned.
I would be interested to learn more of the writing process (if you have time). How does this work with so many authors? Which section(s) did you write?
PaulM
I wrote section 2.5 of chapter 2 (and contributed to other bits here and there, both in this chapter and others). Yes I really must get round to writing a discussion piece on the report preparation process!
The other relevant chapter is 9 (Understanding and Attributing Climate Change), and also Ch 1 "Historical Overview of Climate Change Science".
OK, sorry Paul and Andrew, maybe I was a bit too flippant in my response to Philip, you do have to use the reference lists to trace things back to their original sources. Ch1 section 1.4.1 cites some of the historically important papers such as Tyndall (1861) on absorption of radiation by H2O, CO2 etc.
Richard Betts:
I'm sorry, but as a physicist I seek more than a few words like "the evidence is in the reports". That's not how I was taught physics or produced my thesis. Where is the evidence exactly? I've looked for several years and I've asked the government boffins to tell me where to find it, but they all come back with your answer "it's in the IPCC WGI reports". Nobody has ever pin-pinted any piece of evidence.
I guess you aren't a physicist, but quoting a paper from 150 years ago is a bit much. I think you may find that since then we have had Rutherford and the atom, Einstein and relativity, Feynmann and quantum mechanics and on and on. Nobody believes that the physisicts of 150 years ago had any idea what the properties of CO2 were or how it could affect the flow of energy throught the atmosphere.
You can surely do better than that and come up with a convincing hypothesis backed up by some convincing evidence. Or better still some, evidence to destroy the hypothesis that all the climate change that we have observed since the start of the industrial revolution, is natural.
Richard, thank you for engaging here and thanks for explaining which bits you wrote (I guess I could have searched for the Betts citations!)
Please be careful not to underestimate the people commenting here. As Phillip says, we are all too used to being fobbed off with "it's in the IPCC report" and "it was all explained by Arrhenius".
Are you aware that there is a significant error in the bit just before your sec 2.5?
The median cloud albedo is not -0.7, it is about -1.0. So Fig SPM 2 and FAQ 2.1 Fig 2 are wrong. You can see they are wrong since the blue bar is nowhere near the middle of the error bars - and you can check by doing the sums.
Hi Philip
Why do you guess I'm not a physicist? Actually I am - Bristol (1991). Most scientists at the Met Office are either physicists or mathematicians.
I accept that simply saying "it's in the IPCC report" was a bit lazy of me - sorry about that - but I have to say that dismissing a paper simply on the grounds that it is 150 years old is equally lazy. Yes science moves on, but a lot of things discovered in those days (and earlier) are still accepted and have even been strengthened in the intervening period.
And, although I hate to resort to the "argument by authority" or "argument by consensus" (both also lazy!), I have to say that most sceptics accept that CO2 has a warming influence. For example, Christopher Monckton speaks of "the real scientific consensus to the effect that carbon dioxide causes some warming (in fact, an elementary and proven result in the physics of radiative transfer)" (Foreword to The Climate Caper by Garth Paltridge, page 2)
So, having provided you with a seminal paper which provides the evidence you asked for, and which is accepted by the vast majority, I think the ball is now in your court to present the evidence that refutes this!
Philip Bratby
I know you are in dialogue with Richard, but if I may?
The best synoptic treatment of the physical properties of CO2 I know of is here. While I do not claim that it will necessarily answer all your questions, it will doubtless answer some.
As you are a physicist, I will risk a few more links to the same excellent, if unfortunately titled source.
And there's plenty more in there if you want to investigate specifics.
Richard:
Pleased to hear you are a physicist! Perhaps I should have worked it out. It's just that virtually all the spokespersons for establishment climate science are not physicists.
If you hate resorting to the "argument by authority" or "argument by consensus", then don't do it. Christopher Monckton may be a good speaker, but he doesn't cut the mustard.
I look for you to provide evidence to disprove natural climate change as an explanation for the last 150 years of our climate.
All my career, my work was independently checked and checked and checked by others. I know evidence when I see it. I would just like somebody to point me to one piece of evidence that shows human emissions of CO2 are warming the planet. Tyndall's work is not evidence of that. It is just one small piece in a very complex jigsaw.
BBD
Why did I guess you were pointing me to SoD? I'm still suspicious of any arguments that average conditions over the earth's surface, so I don't accept his explanation. Now Joseph Postma.... tell me where he's goign wrong.
Philip
You aren't going to learn much with an attitude like this.
BBD:
You mean I learn by accepting and by not being suspicious?
Phillip Bratby:
What averaging didn't you agree with?
If you want to see the formal equations of radiative transfer explained - see Atmospheric Radiation and the “Greenhouse” Effect - Part Six – The Equations. Not much averaging in those equations.
If you want to see theory (as shown in that link) matched up with measurements - see Theory and Experiment – Atmospheric Radiation.
If you want a paper which explains how the radiative transfer equations, along with convection, provide a 1-d solution to calculate radiative forcing - see CO2 – An Insignificant Trace Gas? Part Five which includes a link to the Ramanathan & Coakley 1979 paper.
Of course, work from the 1960's and 1970's has all been incorporated into standard textbooks and later papers. Standard textbooks: Atmospheric Radiation:Theoretical Basis by Goody & Yung (1989) and Radiation and Climate by Vardavas & Taylor (2007).
As you originally wrote that you wanted evidence how CO2 affects climate I'm not sure what specifically to explain - it's a broad field.
I will be interested to find out what specific averaging technique(s) I have used that invalidates the explanations of how CO2 and other radiatively-active gases affect climate.
PaulM:
Thanks for the comment on the cloud albedo RF estimate (and indeed for inspecting the chapter so closely). Nice to have someone read it properly!
But why do you think the median value is wrong? The median does not have to be in the middle of the uncertainty range if the distribution of results from the different studies (as shown in table 2.7 and figure 2.14) is asymmetric.
BTW good stuff by BBD and Science of Doom, thanks for posting that, much more accessible than my clumsy attempts!
Philip:
Another useful paper is this one by John Harries and co-authors which uses satellite observations of outgoing longwave radiation to directly detect increases in the Earth's greenhouse effect due to CO2, CH4 and other anthropogenic GHGs.
Unfortunately, although you can read the abstract, the full paper is behind Nature's paywall unless you are a Nature subscriber - but if you email me I'll send you a pdf. (My email is easy to guess)
I'm so chuffed that we're now seeing a sensible and 'respectful' dialogue between previously disengaged parties.
If this trend continues and, one day, leads to meaningful dialogue between RC and CA then, truly, the scientific method has triumphed!
I think it's here (full; very small pdf)
Philip Bratby
I mean we learn by being open-minded and thorough.
What a wonderful thread!
But I am still not sure whether I should burn logs from trees that prove CO2 is warming the planet or not.
Which trees should I chop down? If any?
Or does it matter?
Golf Charley
Concentrate on the energy policy response to AGW. Never mind the trees ;-)
Off to bed now.
That Harries, Brindley, Sagoo & Bantges paper along with 2 others was discussed in American Thinker.
In American Thinker – the Difference between a Smoking Gun and a Science Paper I commented on “The AGW Smoking Gun”, using one of the other similar papers: Changes in the earth’s resolved outgoing longwave radiation field as seen from the IRIS and IMG instruments by Brindley, Sagoo, Bantges and Harries (note same authors).
That article might be of interest as it includes many of the graphs from the paper along with a discussion.
I've opened a discussion topic on the process for writing and reviewing IPCC AR5, since a few people had said they'd like more info on how it actually works.
SoD:
Thanks for your input and all the good work you have done on your site. It is a source of useful information.
What I am not happy with is the averaging of the solar input over the earth's surface and the averaging of the earth's temperature. Averages (if they mean anything) hide a lot of information and can be very misleading.
Phillip Bratby:
Thankyou for your kind comments.
Averaging is, of course, a way of hiding information as much as gaining insight. But some kind of overview is often necessary and this is the reason why I have presented some information via averages.
But if you take, for example, Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part One you can see the inappropriately-named "greenhouse" effect displayed via total power at the surface and at the top of atmosphere - specifically to avoid the averaging problem.
I comment on some problems of temperature averaging in Lunar Madness and Physics Basics and Why Global Mean Surface Temperature Should be Relegated, Or Mostly Ignored.
I think of averaging as useful first steps to get a grasp of climate. Many "debunkings" of atmospheric physics then take some simple models with averages and point out their problems, believing that they have actually addressed a real issue in atmospheric physics rather than a simple teaching model.
But the core equations that govern the absorption and re-emission of radiation in the atmosphere (the radiative transfer equations) - and the results that follow - don't rely on these averaging concepts.
Many papers have been written on radiative forcing specifically on the topic of what global resolution is needed to achieve accuracy in the "overall" radiative forcing value. However, not much point going into that if you have a question on/problem with/alternative solution to, the application of the radiative transfer equations in the atmosphere.
Richard, it is disappointing that immediately after I ask you not to underestimate people here, you continue to do so. As I said, I did the sums. As this is way off topic, I will put it on the discussion board.
Sorry PaulM, I didn't mean to underestimate you - if you can explain your sums I'll definitely look at it. See you on your discussion topic.
The reason that Spencer’s recent paper finds more radiation escaping to space than the models show is because the radiative transfer calculations are done incorrectly. The paper by Ramanathan and Coakley (1979), which is really an update of Manabe and Wetherald (1967), makes the critical error of an instantaneous doubling. The instantaneous doubling approach is a simplistic thought experiment and it yields the wrong answers. The thought experiment, as posed, is physically impossible. The correct way to do the calculations appeared in the scientific literature in 1928. The 1928 approach gives answers in agreement with Spencer.
You can read the older literature or just continue doing incorrect climate modeling. I have been pointing this error out to people since 1979.
Douglas Hoyt:
" The paper by Ramanathan and Coakley (1979), which is really an update of Manabe and Wetherald (1967), makes the critical error of an instantaneous doubling. The instantaneous doubling approach is a simplistic thought experiment and it yields the wrong answers. The thought experiment, as posed, is physically impossible. The correct way to do the calculations appeared in the scientific literature in 1928.."
Can you explain further?
Of course, instantaneous doubling is a simplistic thought experiment and no one (in climate science) is confused by this. The idea is to determine simply what changes between "case 1" and "case 2" - and because the climate is expected to adjust to the radiative forcing by increasing surface temperature it is easiest to describe this via a hypothetical instantaneous change.
Anyway, I look forward to finding out more about your idea.
I think it would be better if you think it through for yourself.
Douglas Hoyt:
"I think it would be better if you think it through for yourself."
Great answer.
It seems like you are saying: "It's so obvious only an idiot could fail to see my point".
If that's the case, you can just say it out loud. Unfortunately, I'm not nearly as smart as Ramanathan or Manabe or Wetherald, so you will have to spell out the details. Think of me as an idiot who would like to learn more and make your case point by point.
Douglas Hoyt
I'm significantly less intelligent than SoD, so I'd appreciate the detail supporting your comment at Aug 10, 12:10pm even more. Do go on.
The Harries et al Nature paper is an interesting example of climate science. To start with it seems that the graphs are labelled the wrong way round in Fig 1a.
The observations show a slight difference in the CO2 band and CH4 band, compensated by a difference of opposite sign elsewhere. Being climate scientists, the authors accept the data where it fits their theory, but try to dismiss the compensating difference as some sort of instrumental difference or 'contamination'.
As I said above, it is time for people to think the problem through for themselves. If they can’t do that, so be it. Spoon feeding doesn’t work if people strongly hold a different view.
On a related note, there seems to be too much trust in the authority via the consensus argument. This can lead people widely astray. As an example, there was an 1896 paper demonstrating that the interior rotation of the sun and stars is cylindrical in shape. The mathematical proof in that paper was considered to be ironclad. By the 1970s, elaborate computer models were being run showing the rotation following cylinders. Then along came helio-seismology which showed the computer models and earlier mathematical derivation were wrong. The rotation followed disc shaped contours. An alternative mathematical derivation in a French journal in the 1920s got the rotation reasonably correct, but people were so wedded to the earlier viewpoint that the newer derivation was ignored.
The point being made is that theoretical results can be wrong for extended periods, as in the above case for more than 80 years. Only observations, rather than an alternative theoretical explanation, can bring the models down. It appears Spencer has done this.
Concerning the Harries paper, I thought that he withdrew it after people pointed out some errors in it.
PaulM:
"To start with it seems that the graphs are labelled the wrong way round in Fig 1a."
The first time I read the paper I thought the exact same thing. But 1 minute of work identified the errata from 26 April 2001 which says:
Nature 410, 355; 2001 In Fig. 1a of this paper, the labels for the two curves were inadvertently switched.
-
"Being climate scientists, the authors accept the data where it fits their theory, but try to dismiss the compensating difference as some sort of instrumental difference or 'contamination'."
My understanding of science generally is that when experimental data has some inconsistencies with well-established theory, some kind of explanation is required.
I see only two possibilities - the data has some problems or the theory has some problems (or a combination).
Let's take an analogy with the theory of gravity - and this is by way of illustration only, analogies do not prove anything. Let's say that someone does some measurements of the orbital fluctuations of Jupiter and finds that the results mostly match the theory of gravity but with some problem areas that cannot be explained. Would the readers here feel that science was done by reaching the conclusion in the relevant journal "obviously the theory of gravity is suspect"?
If you come from the standpoint that this theory of radiative transfer is some kind of made of bodge to prove some stuff about climate that a bunch of people want to hear.. well, obviously, then, from that point of view, a measurement issue is just the final straw for the flawed theory.
It's just that the theory of radiative transfer is extremely well-established, both from theoretical first principles and from experiment. Many textbooks over more than 50 years and thousands of papers from a number of different fields support it.
1. What theory would you like to put forward for the interaction of radiation with the atmosphere?
2. What exactly is it that you think they haven't properly explained?
Doesn't inspire much confidence in the authors, reviewers or Nature editors, does it?
And a more natural explanation of the enhanced LW radiation would be the slight increase in temperature from the 70s to the 90s. That doesn't seem to occur to them so they invent some story about contamination and ice crystals.
PaulM:
"And a more natural explanation of the enhanced LW radiation would be the slight increase in temperature from the 70s to the 90s. That doesn't seem to occur to them so they invent some story about contamination and ice crystals."
Let me help out readers who are interested in understanding the paper. Those who are well ahead of scientists like Professor of Physics John Harries with 80+ peer-reviewed publications to his name of course won't be interested in the details.
"The window difference spectrum could be influenced by changes in surface temperature (assuming constant oceanic emissivity), humidity of the lower troposphere, aerosol content, or cloud amount and type."
So yes, of course, surface temperature changes are considered.
"Consistently, the difference in the 1,100–1,200 cm-1 window is close to zero (within 1 K), while the difference in the 800–1,000 cm-1 region is positive, and lies between about 1 and 2 K. It is important not to over-interpret the observations to an accuracy that is not justified by the errors (see below), nor to lose sight of our principal result, which is the observation of the sharp spectral features discussed in the preceding paragraph. Nevertheless, we believe that this reproducible difference between the windows is consistent with small residual amounts of ice cloud in both averaged spectra, possibly exacerbated by the different fields of view of the two instruments: we discuss this further below."
If surface temperature was responsible then we would see an increase equally in both sides of the "window" region. Instead we observe an increase only in the 800-1,000cm^-1 region - this can't be explained by surface temperature increases.
So the authors of the paper consider the crazy idea that there could be a physics-based reason for this..
"However, recent work [25] has shown that ice cloud, particularly if composed of small crystals, does exhibit stronger absorption in the 800–1,000 cm-1 than the 1,100–1,200 cm-1 window. It is quite possible that small residual amounts of ice cloud absorption remain in both sets of data. Owing to the larger field of view, the IRIS spectra have a much higher probability of being contaminated than their IMG counterparts. The observed 1 K or so enhancement of the 800–1,000 cm-1 difference signal would be consistent with this, and could also arise from a change in the mean cirrus microphysical properties. We cannot separate these two effects, but we do conclude that the observed window difference spectra strongly indicate an effect involving residual small ice crystal effects, incompletely cleared from the data.."
What is the residual cloud-absorption data they are talking about? They attempted to remove the effects of clouds to consider only clear-sky results. This is an imperfect process when very thin clouds are present. Given that small ice crystal clouds do have the "signature" detected in the results it points towards this as the reason.
Like I said, many readers here are well ahead of Professors of Physics from places like Imperial College, London in their understanding of radiative transfer in the atmosphere, and we can only hope that the blog owner lets some of them write articles demonstrating their own insights in the field.
On a personal note, I can hardly wait for that day.